Recent Tendency in Aerospace, Robotics, Manufacturing Systems, Energy and Mechanical Engineering

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Authors: Radu Vasile, Octavian Bologa
Abstract: The present paper describes the current status of hydroforming technology in today’s global market that focuses on energy use in respect to increasing requirements especially from the automotive industry with its renaissance after the economic crisis. A vast hydroforming classification and the restrictions and drawbacks for a wider market share are also presented.
Authors: Abdul Kareem Jalil Kadhim, Ragad Aziz Neama
Abstract: Multi-point Sheet metal forming is a flexible technique in which a discrete punches are used to generate the continuous 3-D surface . The proposed die comprises a set of matrices of a closely stacked discrete punches arranged to form a cavity in which a free form surface can be formed .The working surface of the multi-point die are modeled by a uniform B-spline and constructed by adjusting the height of each punch manually. Finite element simulation for the process was performed to study the effect of punch number on the shape error and thickness variation. Experimental work include the building of multi-point die to form the aluminum sheets. The effect using rubber interpolators on dimpling defect were also studied . The results revealed that thickness variation error between the numerical and experimental results is equal to 5% .
Authors: Gheorghe Matache, Alexandru Paraschiv, Cristian Puscasu
Abstract: The wear behaviour of thick molybdenum coatings deposited by electric arc thermal spray on steel support was investigated by micro-abrasion, a relatively recent introduced method for small scale wear testing. The wear mechanisms and wear rates without coatings penetration were investigated with respect of time corresponding to primary and secondary wear stages. The micro-abrasion of Mo coatings using SiC abrasive slurry have been discussed and wear scar characteristics were evaluated based on the experimentally results. The worn surfaces of the tested specimen were examined by SEM and the specific wear rate was calculated from experimental data. For the testing durations used it was identified the change from grooving to rolling wear corresponding to the transition of wear mode from two-body to three body-abrasion.
Authors: Petrică Corabieru, Stefan Velicu, Anişoara Corabieru, Dan Dragos Vasilescu, Ionel Păunescu
Abstract: The novelty technology lies in the fact that the hardening of the surface layers is carried out both in liquid phase and in the solid state. Technology comprises three main stages with 12 technological phases.Experimentation highlights the viability of the technological procedure. The results of tests and verifications are the basis of the analysis of combined machined parts behavior in conditions similar to the operating conditions and of the analysis of the dependence between operation behavior and durability. Analysis of the results revealed the fact that failure to technological parameters: casting temperature; hold time at high temperatures; cooling rate after microalloying in liquid phase, gives rise to possible faults of the combined treated parts.
Authors: Adinel Gavrus, Daniela Pintilie, Roxana Nedelcu
Abstract: The present research paper concerns a numerical and experimental analysis of the tribologic and rheological constitutive behavior influence on prediction of metallic material forging fibering. Numerical analysis using finite element Forge® code and Abaqus software show the high importance of the friction law formulation and of the material rheological softening on the fibers morphology and on their position coordinates. Calibration and sensitivity of friction law together with the numerical sensitivity of the softening term corresponding to a Hansel-Spittel rheological equation have been studied for a cylindrical crushing test of a 16MnCr5 steel.
Authors: Adina Cristina Toma, Ioana Luminita Dragasanu, Marius Deaconu, Dragos Mihai
Abstract: Commonly, millions of employees are exposed to occupational health issues, including noise exposure during working hours. Noise is most encountered in industry sector but can also be found in a wide range of other workplaces (airports, concert halls, offices, etc). In this article, we review the noise levels inside a machine shop, for a single working place, with the scope to assess the occupational safety, discuss research approach in identifying the noise issues, control and reduce it. Generally, noise exposure is an expensive issue, with many particularities to be solved and the exact cost is difficult to calculate. This study offers the perspective of what can be done for similar working places and how to perform this in order to protect the employees to be noise exposed above the legal noise limits and relevant conclusions are offered in this direction.
Authors: Adriana Comanescu, Claudiu Zaleschi, Liviu Ungureanu, Ileana Dugaesescu, Cristian Alionte
Abstract: The paper deals with the structural synthesis of bi-mobile mechanisms based on six links passive modular groups and used in robotics and other industrial equipment [1]. Such mechanisms are useful in any practical situation when a suitable curve is necessary to be described in manufacturing processes. Even if the passive complex modules with six links are mentioned in the literature these are rarely encountered in construction of mechanisms and in design due to the difficulties to achieve their mathematical models.
Authors: Ivo Malakov, Velizar Zaharinov, Georgi Dinev
Abstract: The paper presents a decision making support system for choosing an optimal variant of technical products. The problem is formulated and its characteristic features outlined. The decision making support system implements various approbated methods for solving the formulated problem. Its capabilities are extended with an advanced algorithm, based on ant colony optimization, and integrated as a program module in the decision making support system. An example problem is solved, showing some of the capabilities of the system, and the integrated algorithm.
Authors: Cătălin Alexandru
Abstract: The work deals with an analytical algorithm for determining the static equilibrium position of the multi-link guiding mechanisms used for the rear axles of the motor vehicles. The method is based on the virtual mechanical work principle, considering the external forces applied to the wheels, as well the reaction forces in the elastic elements of the suspension. The equilibrium position of the guiding mechanism is established relative to the car body, considering the static model of the suspension system, in which the car body is fixed connected to ground (in other words, the car body is the reference part of the system). For determining the reaction forces in the elastic elements of the suspension (springs, bumpers and rebound elements, bushings, anti-roll bar), an original method for the positional analysis of the axle guiding mechanisms was developed and integrated in the mathematical algorithm for establishing the equilibrium position.
Authors: Gabriel Frumuşanu, Alexandru Epureanu
Abstract: The mechanical systems consist of assembled parts, between which diverse interactions take place. Tolerance analysis purpose is to study the effects of part geometric deviations on assembly functional requirements. In the current approaches from this field, the part geometrical deviations are toleranced without considering the evolution of the geometrical deviations during product exploitation. As consequence, between two parts identical as type but with different values of their geometrical features, inside the designed tolerance zones, any difference is made despite they might have significantly different life cycles or manufacturing costs. This paper presents a new conceptual approach concerning parts tolerance design, based on a new criterion, namely the dimensional quality, defined by two important features: life cycle and manufacturing cost. The main issue of this approach is the optimal relation between the manufacturing tolerance zones and the acceptable functional deviation domain. The new concept implementation is sampled in the case of an articulated arm.

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